The laboratory has continued its efforts on genome mapping. We are continuing to develop and map human polymorphic markers. We have identified 70 highly informative microsatellite markers from genomic and cDNA libraries. Many of these markers are embedded within the 3' untranslated regions of expressed genes. These polymorphisms are of particular importance in genetic linkage studies because they highlight the areas of the genome that harbor expressed sequences and they provide immediate candidate genes. On the physical mapping, we have continued the development of sequence tamed sites from partially sequenced expressed genes and we have so far determined the chromosomal origin of 600 of these sequences. The importance of this study lies in the development of an expression map of the human genome which the natural outgrowth and complement of the rapidly progressing genetic and physical maps of the human genome. In the field of genetic mapping we have expanded our search for a major locus involved in Schizophrenia. This search involves 57 small schizophrenia pedigrees, with at least two affected sibs. To date we have typed over 150 markers distributed on all human chromosomes. In the last part of this year we have concentrated on all human chromosomes. In the last part of this year we have concentrated on a promising area of the genome where the preliminary results utilizing the affected pedigree method show highly significant scores in favor of linkage.